[PATCH v3 39/43] drm/rockchip: psr: Avoid redundant calls to .set() callback

Thierry Escande
2018-01-30T20:31:02Z

From: Tomasz Figa <tfiga@chromium.org>

The first time after we call rockchip_drm_do_flush() after
rockchip_drm_psr_register(), we go from PSR_DISABLE to PSR_FLUSH. The
difference between PSR_DISABLE and PSR_FLUSH is whether or not we have a
delayed work pending - PSR is off in either state. However
psr_set_state() only catches the transition from PSR_FLUSH to
PSR_DISABLE (which never happens), while going from PSR_DISABLE to
PSR_FLUSH triggers a call to psr->set() to disable PSR while it's
already disabled. This triggers the eDP PHY power-on sequence without
being shut down first and this seems to occasionally leave the encoder
unable to later enable PSR. Let's just simplify the state machine and
simply consider PSR_DISABLE and PSR_FLUSH the same state. This lets us
represent the hardware state by a simple boolean called "enabled" and,
while at it, rename the misleading "active" boolean to "inhibit", which
represents the purpose much better.

Also, userspace can (and does) trigger the rockchip_drm_do_flush() path
from drmModeDirtyFB() at any time, whether or the encoder is active. If
no mode is set, we call into analogix_dp_psr_set() which returns -EINVAL
because encoder->crtc is NULL. Avoid this by starting out with
psr->allowed set to false.

Signed-off-by: Kristian H. Kristensen <hoegsberg@chromium.org>
Signed-off-by: Tomasz Figa <tfiga@chromium.org>
Signed-off-by: Thierry Escande <thierry.escande@collabora.com>
---
drivers/gpu/drm/rockchip/rockchip_drm_psr.c | 79 +++++++++--------------------
1 file changed, 23 insertions(+), 56 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_psr.c b/drivers/gpu/drm/rockchip/rockchip_drm_psr.c
index c8655e625ba2..448c5fde241c 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_psr.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_psr.c
@@ -22,19 +22,13 @@

#define PSR_FLUSH_TIMEOUT_MS 100

-enum psr_state {
- PSR_FLUSH,
- PSR_ENABLE,
- PSR_DISABLE,
-};
-
struct psr_drv {
struct list_head list;
struct drm_encoder *encoder;

struct mutex lock;
bool active;
- enum psr_state state;
+ bool enabled;

struct delayed_work flush_work;
struct work_struct disable_work;
@@ -78,52 +72,22 @@ static struct psr_drv *find_psr_by_encoder(struct drm_encoder *encoder)
return psr;
}

-static void psr_set_state_locked(struct psr_drv *psr, enum psr_state state)
+static int psr_set_state_locked(struct psr_drv *psr, bool enable)
{
- /*
- * Allowed finite state machine:
- *
- * PSR_ENABLE < = = = = = > PSR_FLUSH
- * | ^ |
- * | | |
- * v | |
- * PSR_DISABLE < - - - - - - - - -
- */
- if (state == psr->state || !psr->active)
- return;
-
- /* Already disabled in flush, change the state, but not the hardware */
- if (state == PSR_DISABLE && psr->state == PSR_FLUSH) {
- psr->state = state;
- return;
- }
+ int ret;

- /* Actually commit the state change to hardware */
- switch (state) {
- case PSR_ENABLE:
- if (psr->set(psr->encoder, true))
- return;
- break;
-
- case PSR_DISABLE:
- case PSR_FLUSH:
- if (psr->set(psr->encoder, false))
- return;
- break;
-
- default:
- pr_err("%s: Unknown state %d\n", __func__, state);
- return;
- }
+ if (!psr->active)
+ return -EINVAL;

- psr->state = state;
-}
+ if (enable == psr->enabled)
+ return 0;

-static void psr_set_state(struct psr_drv *psr, enum psr_state state)
-{
- mutex_lock(&psr->lock);
- psr_set_state_locked(psr, state);
- mutex_unlock(&psr->lock);
+ ret = psr->set(psr->encoder, enable);
+ if (ret)
+ return ret;
+
+ psr->enabled = enable;
+ return 0;
}

static void psr_flush_handler(struct work_struct *work)
@@ -131,10 +95,8 @@ static void psr_flush_handler(struct work_struct *work)
struct psr_drv *psr = container_of(to_delayed_work(work),
struct psr_drv, flush_work);

- /* If the state has changed since we initiated the flush, do nothing */
mutex_lock(&psr->lock);
- if (psr->state == PSR_FLUSH)
- psr_set_state_locked(psr, PSR_ENABLE);
+ psr_set_state_locked(psr, true);
mutex_unlock(&psr->lock);
}

@@ -176,6 +138,7 @@ int rockchip_drm_psr_deactivate(struct drm_encoder *encoder)

mutex_lock(&psr->lock);
psr->active = false;
+ psr->enabled = false;
mutex_unlock(&psr->lock);
cancel_delayed_work_sync(&psr->flush_work);
cancel_work_sync(&psr->disable_work);
@@ -187,8 +150,12 @@ EXPORT_SYMBOL(rockchip_drm_psr_deactivate);
static void rockchip_drm_do_flush(struct psr_drv *psr)
{
cancel_delayed_work_sync(&psr->flush_work);
- psr_set_state(psr, PSR_FLUSH);
- mod_delayed_work(system_wq, &psr->flush_work, PSR_FLUSH_TIMEOUT_MS);
+
+ mutex_lock(&psr->lock);
+ if (!psr_set_state_locked(psr, false))
+ mod_delayed_work(system_wq, &psr->flush_work,
+ PSR_FLUSH_TIMEOUT_MS);
+ mutex_unlock(&psr->lock);
}

/**
@@ -355,8 +322,8 @@ int rockchip_drm_psr_register(struct drm_encoder *encoder,
INIT_WORK(&psr->disable_work, psr_disable_handler);
mutex_init(&psr->lock);

- psr->active = true;
- psr->state = PSR_DISABLE;
+ psr->active = false;
+ psr->enabled = false;
psr->encoder = encoder;
psr->set = psr_set;

--
2.14.1